The proposed research will involve a kinetic analysis of the subunit assembly process of several normal and abnormal hemoglobins. This process presumably involves the combination of two dissimilar partners to form the Alpha Beta dimer which then aggregates tof orm the Alpha 2 Beta 2 tetramer. The isolated heme subunits themselves are oligomeric adding an additional step of complexity to the overall process. Since the absorption spectrum of the isolated heme chains is distinct from that of the intact hemoglobin tetramer, the above reactions can be monitored using either a recording spectrophotometer or a stopped flow apparatus. The Alpha Beta dimer aggregation process will be also investigated by studying human hemoglobin variants which possess unique Alpha Beta interface regions. This research scheme will also evaluate the role of globin-heme reaction in the overall building process. It is unknown where during the tetramer assembly the heme moiety is inserted into the polypeptide chain, but addition of this prosthetic groups is essential for hemoglobin stability and function. The kinetics of the globin-heme reaction can be monitored spectrophotometrically in a stopped flow device. The proposed work will involve a comparision of the rates of heme binding and protein folding of apohemoglobin (Alpha 0 Beta 0), semi-hemoglobin (Alpha Heme Beta 0 or Alpha 0 BetaHeme) and chain globin (Alpha 0; Beta 0) specia of normal and sickle hemoglobin. The rate of assembly of the hemoglobin tetramer, as well as the rate of insertion of the heme moiety, may be important post-translational detriminants of the ultimate distribution of hemoglobins in the erythrocytes of normal individuals and those with various hematological disorders.